Geochemistry and provenance of the Turquoise Bluff Slate, northeastern Tasmania: tectonic significance

摘要: The Ordovician Turquoise Bluff Slate in northeastern Tasmania is a 2 km-thick sequence of deep-marine siliceous black slates. It dominated by meta-siltstones with bimodal grainsize distributions typical turbidite TE-1 and TE-2 facies. slates have high SiO2 indicating they are hemipelagites. Ba V indicate were deposited an anoxic environment associated oceanic productivity. All these features common muddy turbidites. U–Th–Pb dating detrital monazite authigenic xenotime the supports previous evidence that dominant cleavage, this unit, formed during Benambran Orogeny. whole-rock composition similar to Adaminaby Group, NSW. A review Paleozoic compositions from Lachlan Orogen confirms all trace element contents average Australian shale. However, there subtle differences composition. other Mathinna Supergroup rocks Eastern Terrane higher Cr content than age turbidites Victoria This probably reflects small contribution Cambrian ultramafic provenance. If correct, was closer western provinces Orogen, southeastern Australia. Other sedimentary it may be possible recognise provincial variations will provide new constraints on tectonic models